Analytic Stage-Discharge Formulas for Flow in Straight Prismatic Channels

Liao, Huasheng; Knight, Donald W.

doi:10.1061/(asce)0733-9429(2007)133:10(1111)

Cited by 46 publications

(33 citation statements)

References 11 publications

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“…where τ b is local boundary shear stress and U ddepth averaged velocity equals to (Liao and Knight, 2008):…”

Section: Quasi-two-dimensional Skm Modelmentioning

confidence: 99%

“…Uncertainty of model parameters is one of the major uncertainty sources in model results. Although several calibration and case studies has been done on the SKM over past decade (Tang and Knight, 2008;Liao and Knight, 2008;Seckin et al, 2009;Unal et al, 2010;Webr and Menendez, 2004;Knight et al, 2007) but the uncertainty of its simulation results in prediction of velocity distribution, boundary shear stress and discharge capacity has not yet been studied. So, the main aim of this paper is to develop a framework for analyzing uncertainties of quasi-two-dimensional SKM, which are resulted from its global calibration.…”

Section: Introductionmentioning

confidence: 99%

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Uncertainty Analysis of Quasi-Two-Dimensional Flow Simulation in Compound Channels with Overbank Flows

Riahi-Madvar¹,

Ayyoubzadeh²,

Namin³

et al. 2011

Journal of Hydrology and Hydromechanics

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Flow in compound channels with overbank flows becomes more complex because of shear interactions between flows in main channel and flood plains, lateral momentum transfer and secondary flows. Compound channels have interesting applications in flood control, civil engineering and environmental management. Because it is difficult to obtain sufficiently accurate and comprehensive understandings of flow in natural compound rivers, the developed models of flow in overbank flows have many uncertainties. The main aims of this paper are to analysis and quantify the uncertainty results of quasi two dimensional flow modeling in compound channels. In this paper a quasi two dimensional depth averaged model, known as Shiono and Knight Model (SKM), in compound channel is used and uncertainty analysis of its simulation results is done based on Monte-Carlo simulations. Results indicated that although the SKM model can simulate quasi-two-dimensional flow accurately but it has many uncertainties in simulation results. The uncertainties of model results in high are greater than low flows. Also uncertainties in discharge capacity and shear stress are greater than those for velocity profiles. Overall results cleared that the SKM model, beyond from its strong physical basics, requires rigorous effort on local calibration processes, especially for high flood flows and these limit its global applicability and generalities. Prúdenie vody v kanáli so zloženým profilom a s prúdením mimo koryta je javom zložitým, predovšetkým pre interakcie medzi prúdením v hlavnom toku a prúdením v zaplavenom území, ktoré spôsobujú laterálny transport momentu a sekundárne prúdenie. Zložené kanály sa často používajú najmä pri protipovodňovej ochrane, v staviteľstve a v oblasti životného prostredia. Pretože je zložité získať dostatok pesných informácií o prúdení vody v zložených korytách prirodzených tokov, existujúce modely prúdenia vody v zložených profiloch s mimobrehovým prúdením obsahujú veľa neistôt. Cieľom tohto príspevku je analýza a kvantifikácia neistôt vo výsledkoch simulácie kvázi-dvojrozmerného prúdenia v zloženom kanáli s prúdením mimo koryta. V tejto práci používame kvázi-dvojrozmerný vertikálne spriemerovaný model, známy ako model Shiona a Knighta (SKM) pre zložený profil. Analýza neurčitosti je realizovaná metódou Monte-Carlo. Výsledky naznačujú, že model SKM je schopný simulovať kvázi-dvojrozmerné prúdenie pomerne presne, výsledky simulácií sú však značne neurčité. Tieto neistoty sú väčšie ako minimálne prietoky. Taktiež neurčitosti v prietokoch a v tangenciálnych silách sú väčšie ako neurčitosti pre rýchlostné profily. Celkovo výsledky ukazujú, že model SKM, nehľadiac na jeho silný fyzikálny základ, si vyžaduje kalibráciu, predovšetkým pre vysoké prietoky, čo limituje rozsah jeho použitia.KĽÚČOVÉ SLOVÁ. kvázi-dvojrozmerné prúdenie, zložený profil kanála, Monte Carlo, prúdenie mimo koryta, analýza neurčitosti.

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“…where τ b is local boundary shear stress and U ddepth averaged velocity equals to (Liao and Knight, 2008):…”

Section: Quasi-two-dimensional Skm Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Uncertainty Analysis of Quasi-Two-Dimensional Flow Simulation in Compound Channels with Overbank Flows

Riahi-Madvar¹,

Ayyoubzadeh²,

Namin³

et al. 2011

Journal of Hydrology and Hydromechanics

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show abstract

“…Knight et al (2007) analysed the modelling of the boundary shear in trapezoidal channels through investigating the effect of secondary flows on the boundary shear. Liao and Knight (2007) suggested a simple procedure for determining the analytic stage-discharge relationship, involving all three key parameters in SKM model, f, λ, and Г. Rezaei and Knight (2009) employed the SKM to compute the depth-averaged velocity, the boundary shear stress, and the stage-discharge relationship in overbank flow of compound channels with non-prismatic floodplains.…”

Section: Introductionmentioning

confidence: 99%

Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall

2018

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The Shiono and Knight Method (SKM) is widely used to predict the lateral distribution of depth-averaged velocity and boundary shear stress for flows in compound channels. Three calibrating coefficients need to be estimated for applying the SKM, namely eddy viscosity coefficient (λ), friction factor (f) and secondary flow coefficient (k). There are several tested methods which can satisfactorily be used to estimate λ, f. However, the calibration of secondary flow coefficients k to account for secondary flow effects correctly is still problematic. In this paper, the calibration of secondary flow coefficients is established by employing two approaches to estimate correct values of k for simulating asymmetric compound channel with different side slopes of the internal wall. The first approach is based on Abril and Knight (2004) who suggest fixed values for main channel and floodplain regions. In the second approach, the equations developed by Devi and Khatua (2017) that relate the variation of the secondary flow coefficients with the relative depth (β) and width ratio (α) are used. The results indicate that the calibration method developed by Devi and Khatua (2017) is a better choice for calibrating the secondary flow coefficients than using the first approach which assumes a fixed value of k for different flow depths. The results also indicate that the boundary condition based on the shear force continuity can successfully be used for simulating rectangular compound channels, while the continuity of depth-averaged velocity and its gradient is accepted boundary condition in simulations of trapezoidal compound channels. However, the SKM performance for predicting the boundary shear stress over the shear layer region may not be improved by only imposing the suitable calibrated values of secondary flow coefficients. This is because difficulties of modelling the complex interaction that develops between the flows in the main channel and on the floodplain in this region.

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“…Flow depth in the main channel characterized by H and main channel depth was defined by h. Several ways for theoretical methods and soft computing techniques have been proposed for calculating and predicting the flow discharge in compound open channel. In field of theoretical approaches Single Channel Method (SCM) and divided channel method (DCM) as proxy of theoretical methods can be stated (Atabay and Knight 2006;Knight and Demetriou 1983;Knight and Shamseldin 2005;Knight et al 1984;Liao and Knight 2007;Tang et al 1999;Unal et al 2010). In the field of soft computing techniques using the Artificial Neural Networks (ANNs), M5 tree, Genetic Programming (GP), group method of data handling (GMDH) and Support Vector Machine (SVM) can be mentioned (Azamathulla and Zahiri 2012;Noori et al 2009Noori et al , 2016Osooli et al 2011;Parsaie et al 2015a, b;Sahu et al 2011;Unal et al 2010;Zahiri and Azamathulla 2014).…”

Section: Introductionmentioning

confidence: 99%

Flow discharge estimation in compound open channel using theoretical approaches

Parsaie

Najafian

Yonesi

2016

Sustain. Water Resour. Manag.

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Estimating the value of discharge in water ways is an important factor in the flood controlling projects. Recently by advances in flood management, investigators have proposed to use the concept of compound section for modeling the flow characteristics in the natural waterways such as rivers. Several conceptual and theoretical approaches based on the idea of compound section have been proposed for estimating the discharge in rivers. In this study, the performances of the theoretical methods were assessed using performing series of experiments in straight prismatic compound open channel and also analyzing the published data in the literature. Analyzing the performance of theoretical methods shows that Divided Channel Method including vertical bounded line with the determination of coefficient (0.91) and root mean square error (0.02) is an accurate method through the theoretical approaches and only this method has suitable ability to apply for practical purposes.

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Analytic Stage-Discharge Formulas for Flow in Straight Prismatic Channels

Cited by 46 publications

References 11 publications

Uncertainty Analysis of Quasi-Two-Dimensional Flow Simulation in Compound Channels with Overbank Flows

Uncertainty Analysis of Quasi-Two-Dimensional Flow Simulation in Compound Channels with Overbank Flows

Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall

Flow discharge estimation in compound open channel using theoretical approaches

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